1. Field of the Invention
The present invention relates to novel amino acid functionalized macromonomers or polymer precursors, methods for their preparation and novel methods for preparing novel graft copolymers therewith.
2. Description of the Prior Art
It is often desirable to combine two or more polymer systems to obtain a product which exhibits the properties of each system. Most polymers, however, are mutually incompatible in that they cannot be intimately admixed or blended to produce a product having a homogeneous composition.
One solution is to graft copolymerize two or more polymer systems such that the product contains segments of each component homogeneously distributed throughout the copolymer, each contributing its desirable properties thereto.
Although physical blends or mixtures of, e.g., polymers A and B may be incompatible, a graft copolymer of A with another polymer (C) compatible with polymer (B) will enable the production of a homogenous blend of A/C and B. Graft copolymers with segments of dissimilar chemistries have been shown to be useful in a variety of applications as surfactants, compatibilizers, impact modifiers and surface modifiers.
Although it is possible to graft a polymer onto a previously polymerized backbone, these procedures are typically xe2x80x9cmessyxe2x80x9d, often requiring radiation or an energy source to promote grafting. It is usually very difficult to ensure the production of a homogeneous graft copolymer since this type of grafting usually results in a cross-linked base material, as well as a cross-linked layer of grafted polymer.
Most conventional routes to graft copolymers involve employing an intermediate xe2x80x9cmacromonomerxe2x80x9d which is a polymer/oligomer with a functional group capable of undergoing further chemical reaction polymerization. Macromonomers are most often obtained by anionic polymerization. The conditions attendant anionic polymerization, however, severely limit the number and nature of monomers which can be polymerized thereby. Moreover, a majority of the studies thus far have focussed on the synthesis of macromonomers capable of reacting with vinyl monomers to form graft copolymers.
There are few reports of well defined polyamide graft copolymers with addition polymers such as poly(acrylates) or poly(methacrylates). Most attempts of amide graft copolymerizations with addition polymers involve either the in situ formation of graft copolymers in polymer blends or radiation induced surface graft techniques. Although effective for their intended applications, neither method produces a well defined graft copolymer.
It is an object of the present invention to utilize novel free-radical chain transfer methods to create novel macromonomers which are capable of undergoing novel condensation polymerization reactions with polymers to prepare novel graft copolymers.
Another object of the invention is to provide condensation polymerizable macromonomers, more specifically, amino acid terminated macromonomers, and a novel route to the synthesis of polyamide graft copolymers.
The above and other objects are realized by the present invention, one embodiment of which relates to a method of preparing an amino acid functionalized macromonomer composition having a degree of polymerization of from about 5 to about 20,000 comprising reacting by free radical polymerization a mixture comprising:
(a) for chain transfer an amino acid having the formula: 
xe2x80x83wherein:
R1 and R2 are H or lower alkyl, e.g., CH3; and
Z is alkylene, e.g., ethylene, propylene, butylene and the like; arylene, e.g., phenyl, biphenyl; and
(b) at least one polymerizable ethylenically unsaturated monomer, e.g., acrylates, e.g., alkyl acrylate, phenyl acrylate, cycloaliphatic acrylate; methacrylates, e.g., alkyl methacrylate, phenyl methacrylate, cycloaliphatic methacrylate; fluoro-substituted acrylates, e.g., octafluoropentyl methacrylate; fluoro-substituted alkenes such as ethene, propene, butene, butadiene, hexene and octene, such that, as a result of reacting said mixture, at least 10 mol percent of the macromonomer composition product has the end group: 
A further embodiment of the invention comprises a macromonomer prepared according to the above-described method.
Another embodiment of the invention is an amino acid functionalized addition-polymerized macromonomer composition having a degree of polymerization of from about 5.0 to about 20,000.
An additional embodiment of the invention relates to a method of preparing a graft copolymer of a polyamide comprising reacting under condensation polymerization conditions a mixture comprising:
(a) a macromonomer described above, and
(b) a monomeric mixture which forms a polyamide by condensation polymerization.
Other embodiments of the invention comprise a graft copolymer prepared by the above-described method, as well as graft copolymers of a polyamide and the above-described macromonomer composition.